Wireless communication tags are often found in retail and/or warehouse environments, among other environments. The wireless communication tags may be used to track and identify items such as packages, containers, inventory items and articles for inventory, asset management and/or security purposes.
One type of wireless communication tag is a radio frequency identification (RFID) tag. The RFID tag transmits stored information, e.g., information relating to an item using radio frequency (RF) signals. In particular, the RFID tag may include an inlay with an antenna and integrated circuit (IC) chip disposed thereon in which the IC chip is connected to the antenna. The IC chip stores the programmed information, e.g., the information relating to the item. In response to receiving an interrogation signal from an RFID reader, the IC chip converts the programmed information into a corresponding electromagnetic signal which is transmitted by the antenna. The RFID tag is tuned to receive an interrogation signal at a particular frequency or narrow range of frequencies.
However, the performance of the RFID tag may vary depending on various factors. One factor involves the interaction between the inlay and the plastic housing of the RFID tag. For example, when positioned outside and not in contact with the housing, the antenna may exhibit a specific response to the interrogation signal. Placing the substrate with antenna within the housing of the RFID tag, may alter the frequency response of the antenna such that substantially less of the interrogation signal is captured by the RFID tag, i.e., the RFID tag may not “respond” or will respond poorly to the interrogation signal. The interaction or contact between the substrate and housing results in antenna detuning. Moreover, movement of the substrate within the RFID tag may further vary the interaction between the substrate and housing such as to shift the tuned frequency of the antenna. For example, the RFID tag may be attached to an article that is moved around a store or warehouse such that the substrate with antenna is shifted around within the RFID tag which varies the interaction between the substrate and housing. An RFID tag that has become detuned may be unable to receive the interrogation signal as the antenna is no longer tuned to the interrogation signal. In other words, an RFID reader is unable to read or interrogate the RFID tag, or the reading performance is degraded.
Another factor that affects performance of RFID tags is the housing material. For example, loss of signal or antenna detuning may be caused by the lossy characteristics of the plastic housing materials. Moreover, the variations in the housing materials used by different manufactures may also result in tuning variations. In other words, the housing material itself may detune the RFID tag.
Several solutions have been proposed to help maintain RFID tag performance. One solution is to inhibit movement of the substrate within the RFID tag. For example, the substrate may be glued to the housing or the housing may be constructed with a clip-like structure that firmly presses the substrate against the housing. While this solution reduces movement of the substrate, the interaction between the substrate and housing is likely increased. While the tuned frequency of the RFID tag may not vary due to movement, the increased interaction between substrate and housing may have detuned the antenna, i.e., the RFID tag will likely remain detuned.
Another solution involves reducing the interaction between the antenna and the housing by increasing the housing size. In particular, the size of the housing is increased such that the antenna can be positioned away from the inlay support structure of the housing. However, this solution disadvantageously increases the size of tag such as to increase cost of manufacturing and detracts from the aesthetic appeal of the item to which the tag is attached.